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Flashcards in Quality Control Statistics Deck (28)
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1
Q
What is the definition of mean?
A
mathematical average
2
Q
What is the formula for the mean?
A
sum of all the data points divided by number of data points
3
Q
Calculate the mean of 3, 7, 7, 19.
A
= (3+7+7+19)/4
= 36/4
= 9
4
Q
Calculate the median of 3, 7, 7, 19.
A
= (7 + 7) / 2
= 7
in this example, because we have an even number of data points, we take the two in the middle and average
5
Q
Calculate the mode of 3, 7, 7, 19.
A
mode is the most common observation, so the mode is 7
6
Q
What is the formula for determining percent sensitivity?
A
= # disease persons with a positive test result divided by total # Disease Persons multiplied by 100
= TP / (TP + FN)
7
Q
What is the formula for determining percent specificity?
A
= # nondiseased persons with a negative test result divided by total number of nondiseased persons multiplied by 100.
= TN / (TN + FP)
8
Q
What is the formula for determining positive predictive value (PPV)?
A
= TP / (TP + FP)
9
Q
What is the formula for determining negative predictive value (NPV)?
A
= TN / (TN + FN)
10
Q
What is the definition of specificity?
A
probability of correctly classifying a non-diseased person as non-diseased
true negative rate
11
Q
What is the definition of False Positive Rate?
A
probability of correctly classifying a non-diseased person as diseased
12
Q
What is the definition of sensitivity?
A
probability of correctly classifying a diseased person as diseased
true positive rate
13
Q
What is the formula for the False Positive Rate?
A
= FP / (TN + FP) x 100
or
= 1 - specificity
14
Q
What is the formula for the False Negative Rate?
A
= FN / (TP + FN) x 100
or
= 1 - sensitivity
15
Q
What is the formula for the total number of diseased persons?
A
TP + FN
16
Q
What is the formula for the total number of non-diseased persons?
A
TN + FP
17
Q
What is the definition of accuracy?
A
closeness of a measured value to its true value. In other words, the ability to get close to the bulls eye.
18
Q
What is the definition of reproducibility?
A
closeness of repeated measurements of the same quantity. in other words, the ability to hit the same spot on the target.
19
Q
With 'normal distribution', what is the value of observations that will make up the distribution between +/- one standard deviation?
A
68%
20
Q
With 'normal distribution', what is the value of observations that will make up the distribution between +/- two standard deviations?
A
95%
21
Q
With 'normal distribution', what is the value of observations that will make up the distribution between +/- three standard deviations?
A
99%
22
Q
What three conditions can be shown using a Levey-Jennings plot?
A
1. trend
2. shift
3. dispersion
23
Q
Describe a Levey-Jennings plot?
A
plot of control results on the y-axis versus time on the x-axis.
24
Q
What is dispersion?
A
increased frequency of both high and low numbers. the plot has values above and below the line designating 2SD.
25
Q
What is a trend?
A
progressive drift of reported values from a prior mean. the plot shows a drift consistently above or below the line designating 2SD.
26
Q
What is a shift?
A
an abrupt change from the established mean. The plot shows a very abrupt shift above or below the line designating 2SD.
27
Q
What is the number and type of patients that would be tested to establish a reference range?
A
100 patient from the local community.
Include variations in race, sex, age, weight, nutritional status, degree of physical activity, geography, time of day.
The range is established with the 95% confidence limits.
28
Q
When were the CLIA '88 regulations published?
A
2003